It is well known that many liquids such as beverages derived from grains/fruits/vegetables may contain certain polyphenols and proteins which create problems when beverages are mass produced. Specifically, these compounds may cause degradation of flavor and/or appearance for such beverages where they are stored for prolonged periods of time, subjected to variations in temperature, etc. The problem of removing adverse components is made more difficult by the fact that the adverse components are chemically similar to components which are desired in the beverage.
The removal of these adverse components from beverages prior to packaging for sale has been addressed by treating the beverages with various materials designed to adsorb one or more of the adverse components from the beverage. Due to the diverse nature of these adverse components, most treatments have involved contacting of the beverage with a combination of adsorbents, either simultaneously or sequentially. For removal of polyphenolics, certain polyamides have been used such as nylons and polyvinylpolypyrrolidone (PVPP). By far, PVPP has been the most widely used adsorbent for removal of polyphenolics and is considered to be significantly more effective than nylons. For removal of adverse proteins, the adsorbents such as silica gels and tannins have been used.
While PVPP is an effective polyphenol adsorbent, PVPP is an expensive material in the context of treating liquids on a commercial scale. This is especially true for the commercial production of beer and fruit juices. Due to its expense, most users of PVPP regenerate it after use by treatment with basic and acidic solutions. The regenerability of PVPP is limited. Also, the use of regenerated PVPP may result in the introduction of unwanted acid or base into the liquid to be treated. PVPP has further disadvantages in that it is affected by the presence of yeast. Thus, PVPP can be added to the processing of a beverage only after the yeast has been substantially removed. Thus, there is a need for alternative polyphenol adsorbents which provide the adsorption performance of PVPP without its disadvantages.